Wafer level package (WLP) and method for forming the same

Abstract

A semiconductor device structure and method for forming the same are provided. The semiconductor device structure includes a substrate and a conductive pad formed on the substrate. The semiconductor device structure includes a protection layer formed over the conductive pad and a post-passivation interconnect (PPI) structure formed at least in the protection layer. The PPI structure is electrically connected to the conductive pad. The semiconductor device structure also includes a first moisture-resistant layer formed over the protection layer, and the protection layer and the first moisture-resistant layer are made of different materials. The semiconductor device structure further includes an under bump metallurgy (UBM) layer formed over the first moisture-resistant layer and connected to the PPI structure.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a first conductive pad over a chip structure; 
 a passivation layer over the first conductive pad; 
 a first protection layer over the passivation layer; 
 a post-passivation interconnect (PPI) pad extending through the first protection layer and the passivation layer, the PPI pad being coupled to the first conductive pad; 
 an insulating layer surrounding sidewalls of the chip structure and the first protection layer; 
 a second protection layer over the first protection layer and the insulating layer; 
 a PPI structure extending through the second protection layer, the PPI structure being coupled to the PPI pad; 
 a first moisture-resistant layer over the second protection layer and the PPI structure; 
 a ball-like bump over the first moisture-resistant layer; and 
 a second conductive pad over the ball-like bump. 
 
     
     
       2. The semiconductor device of  claim 1 , wherein at least a portion of the passivation layer is disposed between the PPI structure and the first conductive pad in a direction perpendicular to a major surface of the chip structure. 
     
     
       3. The semiconductor device of  claim 1 , further comprising an under bump metallurgy (UBM) extending through the first moisture-resistant layer and along a top surface of the first moisture-resistant layer, the UBM being coupled to the PPI structure, wherein the ball-like bump is over the UBM. 
     
     
       4. The semiconductor device of  claim 3 , wherein the UBM extends along a top surface of the first moisture-resistant layer, and wherein the PPI structure extends along a top surface of the second protection layer. 
     
     
       5. The semiconductor device of  claim 1 , further comprising a substrate over the second conductive pad. 
     
     
       6. The semiconductor device of  claim 1 , wherein the passivation layer extends along a top surface and sidewalls of the first conductive pad. 
     
     
       7. The semiconductor device of  claim 1 , wherein a top surface of the insulating layer is level with a top surface of the first protection layer. 
     
     
       8. The semiconductor device of  claim 1 , further comprising a second moisture-resistant layer over the first moisture-resistant layer, the second moisture-resistant layer comprising a material different from a material of the first moisture-resistant layer. 
     
     
       9. A method comprising:
 forming a conductive pad over a chip structure; 
 depositing a passivation layer over the conductive pad and the chip structure; 
 depositing a first protection layer over the passivation layer; 
 forming a molding compound around the chip structure and the first protection layer; 
 forming a second protection layer over the first protection layer and the molding compound; and 
 forming a first moisture-resistant layer over the second protection layer, the first moisture-resistant layer comprising a different material than the second protection layer. 
 
     
     
       10. The method of  claim 9 , further comprising:
 forming a first opening extending through the passivation layer and the first protection layer to expose a surface of the conductive pad 
 forming a post-passivation interconnect (PPI) pad in the first opening, the PPI pad being coupled to the conductive pad. 
 
     
     
       11. The method of  claim 10 , further comprising:
 forming a second opening extending through the second protection layer to expose a surface of the PPI pad; and 
 forming a PPI structure in the second opening, the PPI structure being coupled to the conductive pad. 
 
     
     
       12. The method of  claim 11 , further comprising:
 forming a third opening extending through the first moisture-resistant layer, the third opening exposing a surface of the PPI structure; and 
 forming an under bump metallurgy (UBM) in the third opening, the UBM being coupled to the PPI structure. 
 
     
     
       13. The method of  claim 9 , wherein the molding compound is formed in contact with sidewalls of the chip structure, the passivation layer, and the first protection layer. 
     
     
       14. The method of  claim 9 , wherein the first protection layer and the second protection layer are formed of the same material. 
     
     
       15. A semiconductor device comprising:
 a semiconductor die; 
 a conductive pad over the semiconductor die; 
 a first protection layer over the conductive pad and the semiconductor die; 
 a molding compound contacting sidewalls of the semiconductor die and the first protection layer; 
 a post-passivation interconnect pad extending through the first protection layer and coupled to the conductive pad; and 
 a solder resist over the molding compound and the first protection layer, the solder resist comprising a material different from a material of the first protection layer. 
 
     
     
       16. The semiconductor device of  claim 15 , further comprising a second protection layer over the molding compound and the first protection layer, the second protection layer being between the solder resist and the molding compound and the first protection layer. 
     
     
       17. The semiconductor device of  claim 16 , wherein the solder resist comprises a material different from the second protection layer. 
     
     
       18. The semiconductor device of  claim 15 , further comprising an under bump metallurgy extending through the solder resist, the under bump metallurgy being coupled to the post-passivation interconnect pad. 
     
     
       19. The semiconductor device of  claim 15 , further comprising a passivation layer over the semiconductor die and the conductive pad, the passivation layer being disposed between the first protection layer and the semiconductor die and the conductive pad, the post-passivation interconnect pad extending through the passivation layer. 
     
     
       20. The semiconductor device of  claim 19 , wherein the passivation layer extends between the post-passivation interconnect pad and the conductive pad in a direction perpendicular to a major surface of the semiconductor die.